Stable Carbon Isotope Variations of Organic Matter and n-Alkanes in the Plant-Bulk Soil-Clay Fraction Continuum

Author

Alana Crump, The University of Western OntarioFollow

Degree

Master of Science

Program

Geology

Supervisor

Dr. Fred J. Longstaffe

Abstract

Organic matter (OM) adsorbed to clay minerals in soils can have C/N similar to lacustrine algal matter. Accurate source identification of OM in sediments is crucial for predicting future climate change impacts in the Great Lakes region. We analyzed C/N, carbon-isotope compositions, n-alkane abundances and compound-specific carbon-isotope compositions of vegetation, soil, and OM associated with clay minerals in soils and glacial till in order to determine if (i) OM associated with clay minerals has unique signatures distinct from lacustrine algal matter and is traceable to modern vegetation, and (ii) if these signatures have been transferred to and preserved in Great Lakes sediments since the last glaciation. OM associated with clay minerals exhibits δ¹³C of ~ –28.5‰ and δ¹³C_n-alkane of –31.5‰; together with together with C/N >10 (but much <20) and n-alkane relative abundance distributions, these signatures are good proxies for C₃ OM sources from higher plants in soils and glaciolacustrine sediments.

Recommended Citation

Crump, Alana, "Stable Carbon Isotope Variations of Organic Matter and n-Alkanes in the Plant-Bulk Soil-Clay Fraction Continuum" (2018). Electronic Thesis and Dissertation Repository. 5827.
https://ir.lib.uwo.ca/etd/5827